This invention relates to both intravascular and non-vascular catheter assemblies. Catheters are commonly employed in percutaneous intravascular procedures, such as percutaneous transluminal coronary angioplasty (PTCA), for example, to open blocked vessels with as little trauma as possible.
Catheters employed for non-vascular procedures include the catheters employed in the urinary tract, or those employed to examine the lower gastrointestinal tract, for example.
Several different types of catheters are utilized for intravascular treatment including guide catheters, angioplasty catheters, dilatation balloon catheters, medical delivery devices such as stent delivery catheters including both the self-expanding and balloon expandable varieties, angiographic catheters, neural catheters, urinary catheters, gastrointestinal catheters, catheters for the reproductive system, heat transfer catheters, therapeutic delivery devices, thrombectomy devices, intravenous ultrasound systems, electrophysiology devices, endoscopic devices, and so on and so forth.
In intravascular procedures, guide catheters are commonly used to aid in delivering a balloon catheter or other interventional medical devices to a treatment site in a vessel or other lumen within the body.
In a routine coronary angioplasty procedure, a guide catheter is introduced through the aorta until the distal end of the guide catheter is engaged with the coronary ostium. Guide catheters typically have a preformed distal tip. The distal portion of the guiding catheter is located within the ascending aorta with the distal tip of the guiding catheter seated in the ostium. The proximal end of the guiding catheter is torqued from outside the patient to guide the distal tip of the guiding catheter into the ostium. Guide catheters typically have preformed bends formed along their distal portion to facilitate placement of the distal end of the guide catheter into the ostium of a patient. Guide catheters preferably have a relatively stiff main body portion and softer distal tip. The stiff main body portion provides the guide catheter with sufficient “pushability” and “torqueability” to allow the guide catheter to be inserted percutaneously through a peripheral artery, moved and rotated to position the distal end of the catheter at the desired aligning angle relative to the ostium. In addition, a soft distal tip at the very distal end of the catheter should be used to minimize the risk of causing trauma to a blood vessel wall while the guide catheter is being moved through the vasculature to the ostium.
Next, the guidewire is advanced past the distal end of the guide catheter within the lumen of the diseased vessel and manipulated across the region of the stenosis. The balloon dilatation catheter is then advanced past the distal end of the guide catheter over the guidewire until the balloon is positioned across the treatment site. After the balloon is inflated to dilate the blood vessel in the region of the treatment site, the guidewire, balloon dilatation catheter and guide catheter can be withdrawn.
Typical commercially available intravascular balloon catheters used for angioplasty and other vascular procedures usually have an elongated shaft with an inflatable dilatation member on a distal portion of the shaft and a fitting on the proximal end of the shaft for the delivery of inflation fluid through an inner lumen extending through the catheter shaft to the interior of the inflatable dilatation member.
Once in position, the balloon is inflated by supplying fluid under pressure through an inflation lumen in the catheter to the balloon. The inflation of the balloon causes stretching of the artery and pressing of the lesion into the artery wall, to reestablish acceptable blood flow through the artery
There are two common types of balloon catheters commonly referred to as “over-the-wire” (OTW) catheters and fixed wire catheters. An over-the-wire catheter is one in which a separate guide wire lumen is provided in the catheter so that a guide wire can be used to establish the path through the stenoses. The dilatation catheter can then be advanced over the guide wire until the balloon on the catheter is positioned within the stenoses. There is also a modification of an OTW catheter which is referred to as a single-operator-exchange (SOE) or rapid exchange (RE) catheter. SOE catheters have a guide wire lumen that only extends through a portion of the catheter. The guide wire lumen extends from the distal end of the catheter to a distal porthole on the catheter tube.
A fixed wire catheter acts as its own guide wire, and thus there is no need for a separate guide wire lumen.
Angiographic catheters can be used in evaluating the progress of coronary artery disease in patients. Angiography procedures are used to view the patency of selected blood vessels. In carrying out this procedure, a diagnostic catheter also having a desired distal end curvature configuration may be advanced through the vascular system of the patient until the distal end of the catheter is steered into the ostium.
The profile of the outer surface of the distal tip of a catheter may be rounded so as to result in a tip which reduces the likelihood of trauma to the vessel. However, rounding the tip on the outside using current methods, may leave the edge of the tip on the inner lumen sharp. When the catheter is advanced over the guidewire, or when the guidewire is retracted into the catheter, this sharp edge can act similar to a knife, scraping material from the guidewire, and can increase the friction between the inner catheter shaft and the guidewire. If a lubricious coating is present, this may also be scraped off. Furthermore, having a sharp tip on the inner lumen can results in parts of the tip which actually break off from the catheter.
There remains a need in the art for a catheter having an inner distal tip which has a smoother, more rounded profile.